Method and apparatus for high density message coding

ABSTRACT

A remote reporting unit, such as freight trailer monitoring device, generates a number of different status messages representing conditions such as door open, latitude, longitude, battery condition, and the like. The remote unit combines the status messages into an optimized output. Optimization is implemented by applying a predetermined mapping scheme to convert the status message&#39;s values into a consolidated output. Having optimized the message, the remote unit transmits the consolidated output in the form of a “feature code” such as a code prefixed by star (*) or another conventional prefix. Telephony equipment that receives the feature code via the cellular telephone network interprets the feature codes by reversing the re-mapping process.

BACKGROUND OF THE INVENTION

I. Field of the Invention

The present invention relates to the use of feature codes in telephony.More particularly, the invention concerns a method of generating,exchanging, and interpreting feature codes that are compressed byre-mapping their contents.

II. Description of the Related Art

A typical wireless telecommunications network includes a large number ofremote switching centers, spread across a broad geographic area.Whenever a remote subscriber places a call, a nearby remote switchingcenter receives the wireless signal for processing. As a remotesubscriber moves between different geographic locations, differentremote switching centers may receive the wireless signal and process thesubscriber's call.

As a matter of convenience to remote subscribers, many wirelesstelecommunications companies permit remote subscribers to dial atelephone number using a special dialing string or “SDS”. A simplifieddialog string is a shortened or abbreviated dialing string, oftenbeginning with a symbol such as the star key (*) or pound key (#) andtypically containing three digits (e.g., *123). When a remote subscriberdials a simplified dialing string, a remote switching center receivesthe simplified dialing string and then translates the receivedsimplified dialing string into a number to be dialed (e.g., *123 may betranslated to 555-1234).

Similarly, many wireless telecommunications companies also support theuse of remote feature codes (“feature codes”). A feature code is similarto a simplified dialing string, but is used as an instruction to controlservice features from a remote subscriber's handset. A non-exhaustivelist of such features includes Call Forwarding, Call Waiting, CallingNumber Identification, Automatic Callback, Conference Calling, MessageWaiting Notification, Call Encryption, Selective Call Acceptance, VoiceMail, Enhanced Vocoder, and Cost of Call Notification. Activation ordeactivation of such features typically involves the completion of asequence of keystrokes on the keypad for selecting or de-selecting thedesired feature. In many cases, the keystrokes involve the entry of anumeric sequence preceded by the star key (*) and/or followed by thepound key (#). An exemplary feature code, for example, might be*66#.Sometimes, feature codes are invoked by the user's selection of adedicated menu by pressing a “Menu” key followed by a one- or two-digitnumber, one or more soft keys, or by scrolling the menu screen. Evenwhen a remote unit has menu capability, the feature code value specificto the home network is commonly a numeric sequence as above, withselection of the “Menu” key being sent as a star key to indicate afeature code. In this case, the feature code value is programmed uponactivation of the feature to correspond to a particular menu location,and the actual feature code value is unknown to the user.

In a typical wireless telecommunications system, translation ofsimplified dialing strings and feature codes occurs within the remoteswitching center processing the remote subscriber's call. Thus, forexample, when a remote subscriber in one geographic location dials *123,a remote switching center in that same location performs the requiredtranslation. In contrast, when the same remote subscriber is in adifferent geographic location and dials the same string/code (e.g.,*123), a different remote switching center will likely process the call.

Because each remote switching center independently translatesstrings/codes into dialed numbers, it is possible that the samestrings/codes will be translated into a different number to be dialeddepending upon which remote switching center performs the translation.For example, if a subscriber in one geographic location, such as Texas,dials *123, the Dallas remote switching center may translate the call todialed number 458-1440. Whereas, if a remote subscriber in anothergeographic location, such as Washington, D.C., the Washington D.C.remote switching center may translate the call to a different dialnumber such as 555-1212. For the same reason, it is also possible thatdifferent remote switching centers will activate/de-activate differentservice features in response to the same feature code processed by thedifferent remote switching centers.

The use of feature codes have been developed and expanded in a varietyof different implementations. Some examples appear in the followingreferences:

-   1. U.S. Pat. No. 6,122,501 dated Sep. 19, 2000, entitled “System and    Method for Flexible Translation of Wireless Special Dialing Strings    and Remote Feature Codes.”-   2. U.S. Pat. No. 6,141,545 dated Oct. 31, 2000, entitled “Method and    System for Remote Call Forwarding of Telephone Calls from Cellular    Phone.”-   3. U.S. Pat. No. 6,029,065, dated Feb. 22, 2000, for “Remote Feature    Code Programming for Remote Stations.”-   4. U.S. Pat. No. 5,913,165, dated Jun. 15, 1999, for “Method for    Changing Subscriber Service Features in a Radio Telecommunications    Network.”

A different use of feature codes has been the recruitment of existingcellular telephone networks to transmit encoded data related totelemetry tracking, surveillance, data transmission, identification, andremote monitoring. One such application involves the exchange ofautomated status messages between cargo trucks and a central monitoringfacility by equipping the cargo trucks with cellular telephoneequipment, and transmitting the messages via “feature codes.” To avoidthe varying significance of feature codes from one cellular serviceprovider to another, remote switching centers typically return callswith feature codes to the subscriber's home service area, which canimplement the feature code as intended by the subscriber. Thus, byequipping a cargo truck's cellular telephone with a MobileIdentification Number (MIN) that indicates that the telephone's homeservice provider is the central cargo monitoring facility, andprogramming the remote switching centers to forward all feature codesfrom phones belonging to that home service provider to the central cargomonitoring facility, the existing cellular network is recruited todirect messages from field equipment to the central monitoring site. Onereference that addresses this subject is U.S. Pat. No. 6,144,859 datedNov. 7, 2000, for “Wireless Cellular Communicator System and Apparatus.”

Although these systems constitute a significant advance and enjoysubstantial commercial success today, engineers at Qualcomm Incorporatedcontinually endeavor to improve the performance and efficiency of suchremote communications systems. With Qualcomm's OmniTRACS® product line,for example, Qualcomm engineers are interested in increasing the speedand efficiency of data flow between remote cargo units and the centralmonitoring facility.

SUMMARY OF THE INVENTION

Broadly, the present invention concerns the use of feature codes intelephony, and more particularly, a method of generating, exchanging,and interpreting feature codes that are compressed by re-mapping theircontents. A remote reporting unit, such as freight trailer monitoringdevice, automatically generates one or more status messages representingconditions such as door open, latitude, longitude, battery condition,and the like. The remote unit combines the status messages into anoptimized output. Optimization is implemented by applying apredetermined mapping scheme to convert the status message's numericvalues into a consolidated output.

Although this mapping may be implemented with a mapping guide such as atable, a more efficient implementation utilizes an appropriatemathematical formula to combine the status messages. For example, theconsolidated output may be calculated by adding the product of eachstatus message with a different coefficient. One example involves addingone status message, plus another status message multiplied by a firstcoefficient, plus another status message multiplied by a secondcoefficient times the first coefficient, etc. The coefficients areselected such that consolidated output can be decomposed into theconstituent status messages by performing series of division operations,with the remainders and the final result providing constituent messages.

Having optimized the message, the remote unit transmits the compressedcode in the form of a feature code such as the consolidated codeprefixed by star (*) or another combination widely practiced intelephony. After the cellular telephony network routes the feature codeaccording to a target processing facility according to known routingprinciples, the target processing facility interprets the feature codesby reversing the re-mapping process.

The foregoing features may be implemented in a number of differentforms. For example, the invention may be implemented to provide a methodof combining one or more status messages into a consolidated output andtransmitting the consolidated output from a remote unit via a cellulartelephone network. In another embodiment, the invention may beimplemented to provide an apparatus such as a remote reporting unit,programmed to combine one or more status messages into a consolidatedoutput and transmit the consolidated output over a cellular telephonenetwork. In still another embodiment, the invention may be implementedto provide a signal-bearing medium tangibly embodying a program ofmachine-readable instructions executable by a digital data processingapparatus to perform optimization and transmission operations asdescribed above. Another embodiment concerns logic circuitry havingmultiple interconnected electrically conductive elements configured toperform optimization and transmission operations as described above.

The invention affords its users with a number of distinct advantages.Chiefly, the optimization aspect of the invention permits remote unitsto convey more information in the same number of messages or use fewermessages to convey the same information, thus conserving valuablebandwidth. By its compression, the invention achieves particular benefitfor use in cellar telephony systems that limit features codes to amaximum length. Also, by transmitting the status messages in the form ofa feature code, the invention benefits from existing infrastructure thatis already configured to receive, route, and process feature codes. Theinvention also provides a number of other advantages and benefits, whichshould be apparent from the following description of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of the hardware components andinterconnections of the hardware environment of the invention.

FIG. 2 is a block diagram of a digital data processing machine accordingto the invention.

FIG. 3 shows an exemplary signal-bearing medium according to theinvention.

FIG. 4 is a flowchart of an operating sequence for preparing,transmitting, and interpreting optimized feature codes according to theinvention.

DETAILED DESCRIPTION

The nature, objectives, and advantages of the invention will become moreapparent to those skilled in the art after considering the followingdetailed description in connection with the accompanying drawings.

Hardware Components & Interconnections

Hardware Environment

FIG. 1 depicts an exemplary hardware environment 100 for use of thepresent invention. A remote reporting unit 106 prepares various statusmessages concerning the status of some equipment being monitored by theunit 106. The remote reporting unit 106 comprises an electronic unitwith some computing capability, and may be implemented in various formsas discussed below. In the illustrated example, the remote reportingunit 106 is installed at a freight trailer 105 of a truck 104, althoughfreight trailers are merely one example, as the remote reporting unit106 may be implemented to monitor other equipment, such as other remoteassets, including passenger automobiles, watercraft, aircraft, andrailcars. In addition, the remote reporting unit 106 could alternativelybe used to report the events or status of fixed remote assets, such asremote electronic meter readers.

The remote reporting unit 106 includes one or more sensors 106 b tomonitor events or conditions of the freight trailer 105 such as: dooropen/close event, cargo events, latitude, longitude, battery condition,tampering with the remote unit 106, software version, etc. The sensors106 b may comprise sensors as utilized in the commercially availableOmniTRACS® system of Qualcomm Incorporated. Some exemplary types ofsensors 106 b include global positioning system (GPS) units, door ajarsensors, battery voltage/current sensors, timers, cargo volume sensors,motion detectors, etc.

The remote reporting unit 106 also includes a cellular telephonytransceiver 106 a, for exchanging messages via a wireless telephonynetwork 102 with a call processing facility 108. As an example, thetransceiver 106 a may comprise equipment as found in the TrailerTRACS®product of Qualcomm Incorporated, which is a trailer position and statusunit for sending trailer-related information to a call processingfacility 108. When the remote unit 106 initiates a call, it is coupledto the network 102 by a wireless connection 110. The network 102completes the call by forming another connection 112 (wireless orotherwise) coupling the call processing facility 108 to the network 102.The call processing facility 108 includes computing equipment toreceive, interpret, and otherwise process incoming calls from remotereporting units 106.

Although other approaches may be used, the environment 100 may avoid thecosts of subscribing to comprehensive voice cellular service byutilizing a network 102 with specialized facilities for conductingbrief, non-voice transmissions. One example is the MICROBURST technologyutility of AERIS.NET, INC. of San Jose, Calif. The MICROBURST technologyutility is a commercially available product for sending short datapackets over the control channels of existing cellular networks, andprovides an economical conduit between the cellular telephoneinfrastructure and low-packet volume wireless data applications. For theMICROBURST utility, AERIS.NET, INC. contracts with cellular companiesand then coordinates distribution channels, such as service providerswith vertical market expertise, to take advantage of an evolvingnationwide, virtual network. AERIS, INC. maintains and operates thevirtual network and a nationwide MICROBURST hub, which acts as thenetwork intelligence.

According to this invention, facilities of the call processing facility108 include computing equipment to receive, interpret, and act uponmessages transmitted by the remote reporting unit 106.

Exemplary Digital Data Processing Apparatus

As mentioned above, the remote reporting unit 106 may be implemented invarious forms. As one example, the remote reporting unit 106 maycomprise a digital data processing apparatus, as exemplified by thehardware components and interconnections of the digital data processingapparatus 200 of FIG. 2.

The apparatus 200 includes a processor 202, such as a microprocessor orother processing machine, coupled to a storage 204. In the presentexample, the storage 204 includes a fast-access storage 206, as well asnonvolatile storage 208. The fast-access storage 206 may comprise randomaccess memory (“RAM”), and may be used to store various parameters,readings, messages, alpha-numeric sequences, and any other datagenerated by processor 202, sensors 106 b, or received over the air byremote reporting device 106. The nonvolatile storage 208 may comprise,for example, one or more magnetic data storage disks such as a “harddrive”, a tape drive, or any other suitable storage device for programinstructions executed by the processor 202. The apparatus 200 alsoincludes an input/output 210, such as a line, bus, cable,electromagnetic link, or other means for the processor 202 to exchangedata with other hardware external to the apparatus 200, such as one ormore sensors 106 b.

Despite the specific foregoing description, ordinarily skilled artisans(having the benefit of this disclosure) will recognize that theapparatus discussed above may be implemented in a machine of differentconstruction, without departing from the scope of the invention. As aspecific example, one of the components 206, 208 may be eliminated;furthermore, the storage 204 may be provided on-board the processor 202,or even provided externally to the apparatus 200.

Logic Circuitry

In contrast to the digital data processing apparatus discussed above, adifferent embodiment of the invention uses logic circuitry instead ofcomputer-executed instructions to implement the remote reporting unit106. Depending upon the particular requirements of the application inthe areas of speed, expense, tooling costs, and the like, this logic maybe implemented by constructing an application-specific integratedcircuit (“ASIC”) having thousands of tiny integrated transistors. Suchan ASIC may be implemented with CMOS, TTL, VLSI, or another suitableconstruction. Other alternatives include a digital signal processingchip (“DSP”), discrete circuitry (such as resistors, capacitors, diodes,inductors, and transistors), field programmable gate array (“FPGA”),programmable logic array (“PLA”), and the like.

Operation

Having described the structural features of the present invention, themethod aspect of the present invention will now be described. Asmentioned above, the method aspect of the invention generally involves amethod of generating, exchanging, and interpreting feature codes thatare compressed by re-mapping their contents. Although the presentinvention has broad applicability to machine-readable status messages,the specifics of the structure that has been described is particularlysuited for sensing conditions of a freight tractor trailer, and theexplanation that follows will emphasize such an application of theinvention without any intended limitation.

Signal-Bearing Media

In the context of FIGS. 1-2, such a method may be implemented, forexample, by operating the remote reporting unit 106, as embodied by adigital data processing apparatus 200, to execute a sequence ofmachine-readable instructions. These instructions may reside in varioustypes of signal-bearing media. In this respect, one aspect of thepresent invention concerns signal-bearing media embodying a program ofmachine-readable instructions executable by a digital data processor togenerate and transmit feature codes that are optimized by re-mapping anumber of constituent status messages. Another aspect of the inventionis a program that is executable by the facilities of the call processingfacility 108 to receive and interpret such feature codes.

In either case, such a signal-bearing media may comprise, for example,RAM (not shown) contained within the remote reporting unit 106 or callprocessing facility 108 (FIG. 1), as represented by the fast-accessstorage 206 (FIG. 2). Alternatively, the instructions may be containedin another signal-bearing media, such as a magnetic data storagediskette 300 (FIG. 3), directly or indirectly accessible by theprocessor 202. Whether contained in the storage 306, diskette 300, orelsewhere, the instructions may be stored on a variety ofmachine-readable data storage media. Some examples include as directaccess storage (e.g., a conventional “hard drive”, redundant array ofinexpensive disks (“RAID”), or another direct access storage device(“DASD”)), serial-access storage such as magnetic or optical tape,electronic read-only memory (e.g., ROM, EPROM, or EEPROM), opticalstorage (e.g., CD-ROM, WORM, DVD, digital optical tape), paper “punch”cards, or other suitable signal-bearing media including analog ordigital transmission media and analog and communication links andwireless. In an illustrative embodiment of the invention, themachine-readable instructions may comprise software object code,compiled from a language such as “C,” etc.

Logic Circuitry

In contrast to the signal-bearing medium discussed above, the methodaspect of the invention may be implemented using logic circuitry,without using a processor to execute instructions. In this embodiment,the logic circuitry is implemented in one or both of the remotereporting unit 106 and processing facility 108, and is configured toperform operations to implement the method of the invention. The logiccircuitry may be implemented using many different types of circuitry, asdiscussed above.

Overall Sequence of Operation

FIG. 4 shows a sequence 400 to illustrate one example of the methodaspect of the present invention. For ease of explanation, but withoutany intended limitation, the example of FIG. 4 is described in thecontext of the environment 100 described above. The steps begin in step402, when the remote reporting unit 106 senses various conditionspertinent to the trailer 105. TABLE 1, below, shows an exemplary list ofthese conditions.

TABLE 1 Exemplary Conditions Sensed by Remote Reporting Unit CONDITIONPOSSIBLE VALUES latitude range: 0-299,999 longitude range: 0-529,999trailer door state open, closed cargo state empty, not empty, unknowndoor event occurred yes, no freight event occurred yes, no cargo eventoccurred yes, no beginning of motion event yes, no occurred end ofmotion event occurred yes, no no event occurred n/a

The foregoing merely constitutes one example. Other conditions may alsobe reported, such as battery condition, e.g., new battery, full charge,needs charge, end of battery capacity, end of battery life, etc. The“door event” could be a sensed change in the door status, for example,the door changing state from “open” to “closed”. The “cargo event” couldbe a sensed change in the cargo status, for example, an empty trailerbeing loaded with cargo. The “freight event” could be defined as a thedoor status combined with a time duration, i.e., a freight event couldbe defined as the door opening for at least a predetermined time period,then closing.

After step 402, the remote reporting unit 106 represents the sensedconditions as various status messages (step 404). Namely, each statusmessage is reported as a numeric value representing one of multiplealternative conditions detected by the remote reporting unit. Oneexample is shown in TABLE 2, below.

TABLE 2 Exemplary Conditions and Their Status Messages STATUS MESSAGE &FORMAT REPRESENTS: LAT 0-299,999 in application-specific units oflatitude LON 0-529,999 in application-specific units of longitude STATE 0 = cargo empty, door closed  1 = cargo empty, door open  2 = cargo notempty, door closed  3 = cargo not empty, door open  4 = cargo stateunknown, door closed  5 = cargo state unknown, door open EVENTS  0 = noevent occurred (ie, report position)  1 = event 1 occurred  2 = event 2occurred  3 = event 1 and 2 occurred  4 = event 3 occurred  5 = event 3and event 1 occurred  6 = event 3 and 2 occurred  7 = events 3, 2, and 1occurred  8 = event 4 occurred  9 = event 4 and 1 occurred 10 = event 4and 2 occurred 11 = event 4, 2, and 1 occurred 12 = event 4 and 3occurred 13 = event 4, 3, and 1 occurred 14 = event 4, 3, and 2 occurred15 = event 4, 3, 2, and 1 occurred EVENTS 16 = event 5 occurred 17 =event 5 and 1 occurred 18 = event 5 and 2 occurred 19 = event 5, 2, and1 occurred 20 = event 5 and 3 occurred 21 = event 5, 3, and 1 occurred22 = event 5, 3, and 2 occurred 23 = event 5, 3, 2, and 1 occurred 24 =coverage query 25 = battery needs replacement-day 1 26 = battery needsreplacement-day 2 27 = battery needs replacement-day 3 28 = battery wasreplaced 1 day ago 29 = battery was replaced 2 days ago 30 = battery wasreplaced 3 days ago

The following is a possible condition of truck 104 and/or trailer 105 asreported to remote reporting unit 106 during typical use and is used asan illustrative example throughout the remainder of the presentdisclosure: LAT=118,620, LON=418,656, STATE=3, EVENT=18. These valuesindicate that the truck 104 and/or trailer 105 is at a latitude of 11hours, 86 minutes, 20 seconds, a longitude of 41 hours 86 minutes, 56seconds, having at least some cargo present (i.e., not empty), having adoor open, and the battery has been in need of replacement for 1 day. Ofcourse, the number and type of events may be different, depending on theapplication.

Events 1, 2, 3, 4, and 5 in Table 2 represent different operating eventsof the apparatus being monitored by remote reporting unit 106. In oneembodiment, event 1 could represent a change in status of a door, event2 could represent a change of status of cargo present, and event 3 couldrepresent a change of status of the motion of truck 104 and/or trailer105.

Event 24 is listed as a “coverage query”. This event may occur forexample, when a vehicle attempts to transmit information for the firsttime at while located in a new geographic area. For example, a trailermay comprise a remote reporting unit 106 which has not transmitted amessage in quite some time. Subsequent to transmitting the priormessage, the trailer was hooked up to a tractor vehicle and transported1000 miles. The remote reporting unit 106 may not know whether it cancommunicate with a local wireless communication system, such as ananalog cellular system. Therefore, prior to sending information over alocal cellular system, the remote reporting unit 106 may transmit amessage to determine whether it is capable of communicating with thelocal cellular system. Such a message is referred to as a coveragequery. If a coverage is in doubt, a message is transmitted by remotereporting unit 106 having an event code of 24. Typically, if remotereporting unit 106 is within a coverage area, the local cellular systemwill transmit an acknowledgement message to remote reporting unit 106indicating that remote reporting unit 106 is indeed within coverage andthat the message information was received successfully. Such anarrangement allows one message containing the coverage query andpertinent operating information to be transmitted, rather than twomessages, one to determine coverage and another to transmit operatinginformation.

The arrangement of events shown in TABLE 2 may be tailored to theapplication for minimizing the number of messages needed fortransmission. For example, it may be advantageous to group a number ofevents which have a high likelihood of occurrence together, as shown inevents 1 through 23. In this example, the occurrence of multiple eventsgenerates only one message. For example, upon loading a trailer 105 withcargo, the door might change state (event 1) from open to closed and acargo sensor might sense a change in cargo state (event 2) from empty tonot empty. Only one message needs to be transmitted in this case: amessage containing event code 3. In another example, the coverage query,event 24, could be grouped with the other 5 predefined events so thatthe current status of the apparatus being monitored could be transmittedin the same message as the coverage query. In other words, instead ofsending one message having event code 24 (coverage query), then anothermessage having event code 15, for example, Table 2 could be arrangedsuch that the coverage query represents a 6^(th) event. TABLE 3represents how the event representation would look.

TABLE 3 EVENTS  0 = 0 = no event occurred (ie, report position)  1 =event 1 occurred  2 = event 2 occurred  3 = events 1 and 2 occurred  4 =event 3 occurred  5 = events 3 and 1 occurred  6 = events 3 and 2occurred  7 = events 3, 2, and 1 occurred  8 = event 4 occurred  9 =events 4 and 1 occurred 10 = events 4 and 2 occurred 11 = events 4, 2,and 1 occurred 12 = events 4 and 3 occurred 13 = events 4, 3, and 1occurred 14 = events 4, 3, and 2 occurred 15 = events 4, 3, 2, and 1occurred 16 = event 5 occurred 17 = events 5 and 1 occurred 18 = events5 and 2 occurred 19 = events 5, 2, and 1 occurred 20 = event 5 and 3occurred 21 = events 5, 3, and 1 occurred 22 = events 5, 3, and 2occurred 23 = events 5, 3, 2, and 1 occurred 24 = event 6 occurred 25 =events 6 and 1 occurred 26 = events 6 and 2 occurred 27 = events 6, 2,and 1 occurred 28 = etc . . .

As one can see, the total number of events would increase due to theinclusion of a coverage query as event 6. However, the number ofmessages transmitted might be reduced significantly in such anarrangement. By grouping those events most likely to occur together, theneed for multiple message transmissions is reduced.

After step 404, the remote reporting unit 106 proceeds to step 406,where it optimizes the status messages. Step 404 is achieved by applyinga predetermined mapping scheme to convert the status message's numericvalues into a consolidated output.

In one embodiment, this mapping scheme may be implemented with a mappingguide such as a table, as shown in TABLE 4.

TABLE 4 Mapping Guide: Consolidated Outputs vs. Constituent StatusMessages CONSOLIDATED CONSTITUENT STATUS MESSAGES (OPTIMIZED) OUTPUT LATLON STATE EVENT  0 0 0 0 0  1 0 0 0 1  2 0 0 0 2  3 0 0 0 3 . . . . . .. . . . . . . . . 30 0 0 0 30  31 0 0 1 0 32 0 0 1 1 . . . . . . . . . .. . . . .

The complete contents of TABLE 4 requires a considerable length topresent all possible combinations of latitude, longitude, state, andevent conditions. A more efficient implementation omits the lengthymapping guide and instead utilizes an appropriate mathematical formulato combine the status messages, and a reverse mathematical formula tode-construct the status messages. Such a formula may be a variation ofknown string packing techniques such as Radix−50, for example. Forexample, the consolidated output may be calculated by adding one statusmessage, plus another status message multiplied by a first coefficient,plus another status message multiplied by a second coefficient times thefirst coefficient, etc. As explained in greater detail below, thecoefficients are selected such that consolidated output can bedecomposed into the constituent status messages by performing series ofdivision operations, with the remainders and the final result providingconstituent messages.

EQUATION 1, below, provides a specific example of one mathematicalformula that may be utilized to consolidate the status messages shownabove.CNO=C3*LAT+C2*LON+C1*STATE+EVENT  [1]

where:

-   -   CNO=the consolidated output.    -   C1=a first coefficient, equal to the number of possible values        that the EVENT variable can occupy, in the present example, 31.    -   C2=a second coefficient, equal to the number of possible values        that the STATE variable can occupy multiplied by the number of        possible values that the EVENT variable can occupy, in the        present example equal to 6*31=186.    -   C3=a third coefficient, equal to the number of possible values        that the LON variable can occupy multiplied by the number of        possible values that the STATE variable can occupy multiplied by        the number of possible values that the EVENT variable can        occupy, in the present example equal to 530,000*6*31=98,580,000.    -   LAT=content of the LAT status message.    -   LON=content of the LON status message.    -   EVENT=content of the EVENT status message.    -   STATE=content of the STATE status message.        Therefore, the consolidated output in the present example would        be equal to:        (98,580,000*118,620)+(186*418,656)+(31*3)+18=11,693,559,600,000+77,870,016+93+18=11,693,637,470,127

After step 406, the remote reporting unit 106 generates a feature codecomprising of the consolidated output, and transmits the feature code tothe call processing facility 108 via the network 102 (step 408). Theconsolidated output may be transmitted as a feature code, for example,by initiating a cellular telephone call containing the output precededby star(*).

In summary, the encoding process can be described generically asfollows, using Table 4.

TABLE 4 Number Of Condition Possible Values A W B X C Y D Z

Table 4 shows conditions A, B, C, and D, corresponding to variousconditions present at freight trailer 105, truck 104, or other vehicleor device being monitored by remote reporting unit 106. In the presentexample, condition A represents latitude, condition B representslongitude, condition C represents State and condition D representsEvent. Each monitoring situation may have the same, or greater or fewerconditions to be monitored. Each of the conditions in Table 4 has acorresponding number of possible values. For example, in the presentexample, the number of possible values of the State condition is 6. Toencode the actual values of the conditions, where the order of theconditions is predetermined, then the following equation may be used(assuming an order of A, B, C, and D, i.e. A being “most significantposition” and D being “least significant position”):CNO=(W*X*Y)*A+(W*X)*B+(W)*C+D

After the feature code is transmitted in step 408, the network 102routes the feature code to the call processing facility 108 (step 410).As one example, to avoid the varying significance of feature codes fromone cellular service provider to another, the network 102 may routecalls with return feature codes to the subscriber's home service area,which can implement the feature code as intended by the subscriber. Byequipping the remote reporting unit 106 with a unique mobileidentificaiton number (MIN) prefix identifying central monitoring site108, such as “175”, and programming the remote switching centers todirect all feature code calls having a MIN prefix equal to “175” to thecall processing facility 108, the existing cellular network can be usedto direct messages from field equipment (106) to a central monitoringsite (108).

In step 412, the call processing facility 108 interprets the featurecode from the remote reporting unit 106. This is performed by utilizingthe mapping guide (TABLE 3) in reverse. Or more expeditiously, step 412may apply a reverse of the formula that was used to prepare theconsolidated output. In the example of EQUATION 1, the consolidatedoutput is de-composed as shown by EQUATIONS 2-4, below.CNO/NUMBER OF POSSIBLE VALUES OF EVENTS------>yields a QUOTIENT1,REMAINDER1 (REMAINDER1=EVENT)  [2]QUOTIENT 1/NUMBER OF POSSIBLE VALUES OF STATE------>yields a QUOTIENT2,REMAINDER2 (REMAINDER2=STATE)  [3]QUOTIENT2/NUMBER OF POSSIBLE VALUES OF LON------>yields a QUOTIENT3,REMAINDER3 (REMAINDER3=LON; QUOTIENT3=LAT)  [4]

Alternatively, the consolidated output is de-composed as shown byEQUATIONS 5-7, below.CNO/C3------>yields a QUOTIENT1, REMAINDER1 (QUOTIENT1=LAT)  [5]REMAINDER 1/C2------>yields a QUOTIENT2, REMAINDER2 (QUOTIENT2=LON)  [6] REMAINDER2/C1------>yields a QUOTIENT3, REMAINDER3 (REMAINDER3=STATE;QUOTIENT3=EVENT)  [7]

Generically, the decoding process can be described as follows (referringback to Table 4).CNO/Z------>yields a QUOTIENT1, REMAINDER1 (REMAINDER1=D)QUOTIENT 1/Y------>yields a QUOTIENT2, REMAINDER2 (REMAINDER2=C)QUOTIENT2/X------>yields a QUOTIENT3, REMAINDER3 (REMAINDER3=B;QUOTIENT3=A)The decoding process may alternately be expressed as:CNO/(W*X*Y)------>yields a QUOTIENT1, REMAINDER1 (QUOTIENT1=A)REMAINDER 1/(W*X------>yields a QUOTIENT2, REMAINDER2 (QUOTIENT2=B)REMAINDER2/W------>yields a QUOTIENT3, REMAINDER3 (REMAINDER3=C;QUOTIENT3=D)

Finally, in step 414, the call processing facility 108 acts upon featurecode that was interpreted in step 412. These actions may involverecording the constituent status messages, sending return messages,transmitting notification of the status messages to an interested party(such as an operator of the trucking line that owns the trailer 105),alerting technical support staff to an urgent condition at the trailer105, etc.

While the foregoing disclosure shows a number of illustrativeembodiments of the invention, it will be apparent to those skilled inthe art that various changes and modifications can be made hereinwithout departing from the scope of the invention as defined by theappended claims. Furthermore, although elements of the invention may bedescribed or claimed in the singular, the plural is contemplated unlesslimitation to the singular is explicitly stated. Additionally,ordinarily skilled artisans will recognize that operational sequencesmust be set forth in some specific order for the purpose of explanationand claiming, but the present invention contemplates various changesbeyond such specific order.

1. A method for transmitting data from a remote reporting unit via awireless communication network, comprising operations of: generating astatus message, said status message having a value representing one ofmultiple alternative conditions detected by a remote unit; applying apredetermined mapping scheme to convert said value into a consolidatedoutput; generating a feature code comprising the consolidated output;and transmitting the feature code to a call processing facility.
 2. Themethod of claim 1, where the operation of applying a predeterminedmapping scheme comprises: multiplying each status message by a differentpredetermined coefficient to create a corresponding multiplicativeproduct; and adding the multiplicative products; wherein thecoefficients are selected to enable reconstruction of each statusmessage by repeated division of the consolidated output by thecoefficients.
 3. The method of claim 1, wherein said status messagecomprises a latitude, a longitude, an event code representing anoccurrence of one or more predetermined events, and a state coderepresenting one or more states.
 4. The method of claim 3, where theoperation of applying a predetermined mapping scheme comprises:multiplying the latitude status message by a first coefficient;multiplying the longitude status message by a second coefficient;multiplying the event code by a third coefficient; and adding results ofthe foregoing multiplication operations to the state to create acorresponding multiplicative product.
 5. A signal-bearing mediumtangibly embodying a program of machine-readable instructions executableby a digital processing apparatus to perform operations for transmittingdata from a remote unit via a telephone network, said operationscomprising: a remote reporting unit for generating a status message,said status message having a value representing one of multiplealternative conditions detected by the remote reporting unit; the remoteunit optimizing the status message comprising operations of: applying apredetermined mapping scheme to convert said value into a consolidatedoutput; and the remote unit generating a feature code comprising theconsolidated output, and transmitting the feature code to a callprocessing facility.
 6. The medium of claim 5, wherein the operation ofthe remote unit applying a predetermined mapping scheme comprises:multiplying each status message by a different predetermined coefficientto create a corresponding multiplicative product; and adding themultiplicative products; where the coefficients are selected to enablereconstruction of the status messages by repeated division of theconsolidated output by the coefficients.
 7. A remote reporting unit,comprising: a first sensor for sensing an first event and generating afirst status; a second sensor for sensing a second event and generatinga second status; a wireless transmitter; data processing circuitry,coupled to said first sensor, second sensor, and said transmitter,configured to transmit reports of the events and status by performingoperations comprising: generating a status message, said status messagehaving a value representing one of multiple alternative conditionsdetected by the first and second sensors; optimizing the status messageby applying a predetermined mapping scheme to the status message toconvert the value into a consolidated output; generating a feature codecomprising the consolidated output; and transmitting the feature code toa call processing facility using said wireless transmitter.